Method and joint for forming tubes from corrugated material



` April 26, 1960 P. MOLLA 2,934,466

METHOD AND JOINT FOR FORMING TUBES FROM CORRUGATED MATERIAL Filed Dec. 28, 1953 2 Sheets-Sheet l INVENTOIL P/ET/P Naz A AGENT April 26, 1960 P. MOLLA 2,934,466

METHOD AND JOINT FOR FORMING TUBES FROM CORRUGATED MATERIAL Filed Dec; 28, 1953 Z Sheets-Sheet 2 i www AGENT METHOD AND JOINT FOR FORMING TUBES FROM CORRUGATED MATERIAL Pietro Molla, Pontenuovo di Magenta, Italy, assignor to S.A.F.F.A.S.p.A. Fabbriche Fiammiferi ed Alni, Milan, Italy, an Italian company Application December 2s, 195s, serial No. l400,504 lClaimspriority, application Italy November 17, 1953 6 Claims. (Cl. 154-83) tective tubes for bottles, fluorescent tubes or the like is,` generally effected in one of the following ways:

-(1). By overlapping the edges of the tubes and stitchring', these edges together with metallic stitches.

Y'(21) By overlapping the edges of the tubes and securing. their edges together with an adhesive.

(3) .By stitching together butt joined edges.

V(4) By the application of a gummed strip of paper to the butt joined edges.

v (5)77By applying an adhesive to the engaging edges of a butt joint. f

Each of the above mentioned methods has Welldelined disadvantages or limitations, especially with regard to the thickness ofthe materials joined, Vwhich is usually rather substantial.

With the first method, vapart from'the disadvantage of forming an unsightly and protruding rib, it has the disadvantage of localizing the tensional forces, with a risk of breakage of the paper at the position of the metal stitches. y Y f j l v kWith the second method, the second of the above mentioned risks is eliminated, but theV unsightly heavy rib rei-nains; `in addition there is aweakening of the joint ,because ofthe diiculty of effecting a good jointing of the two surfaces in jcontact due tothe nature of the corrugated formV of the material. ',With the third method the joint is very side` of the joint, thusforming a rigid rib. v

With the fourth method the unsightly rib is eliminated, but Aan yalmost equally unsightly strip of paper is provided, which is `notstrong when under tension and Vis difficult to apply due tothe corrugated Iform of the materialfto be joined.

f With the fifth method the joint is satisfactory from anaesthetic point of view, but the joint is not resistant to ftensile'stress since the contact surface is reduced to the thickness of the material. Moreover this type of` joint `provides Iak surface which is broken by the corrugated nature of the material.`

,{The object of the Vpresent invention is to provide ahew and improved ,typeof joint andmethod of making the same which eliminates all the disadvantages of the other joints land methodspf forming the same while retaining the advantages of Astrength andv sightliness. g j

The joint'accord-ing to this invention is characterised ,in that it is made by overlapping va longitudinal edge vof the corrugated material'which has been lpreviously cotto size onto the opposite edgef'of the corrugated material which has been suitably flattened to remove the ridges from the material. Preferably'the attened surtates Patent strong, butin Y it is very unsightly as `the stitching in order to have 'strength has to take in aY couple of corrugations on each face of the longitudinal edge of the material has been also folded and knurled.

A joint of this type has the following advantages:

(l) A large contact surface for the jointing.

(2) Better adhesive effect for the adhesive solution due to flattening of the surfaces in contact. v

(3) Continuity of the pattern formed by the corrugations at the joint without alteration of the spacing or pitch of the corrugations.

V(g4) Uniformity of thickness of the finished tube without the formation of a rigid rib at the joint.

(5.) Flexibility at the joint, that is, it -is able to adapt itself to the shape of the object which -is being protected. Y

Tubes joined with this system or method (when a suitable adhesive is applied which may even be the economical sodium silicate) are very resistant totensional forces imparted to themduringuse, such as when a glass bottle or tube is forced into the cardboard tube; further, they are completely satisfactory as far as the aesthetic point of view is concerned because of the uniformity of the thickness of the tube and the continuity of the corrugation pattern.

The invention includes also a process for producing an improved joint.

This invention-will be described in detail in connection with the attached drawings, in which:

VFigure 1 isa schematic view in perspective of a corrugated tube of pliable material which has been joined according to the invention.

Figure 2 is aschematic view showing a rectangle of pliable corrugated paper .to be joined after flattening, folding and knurlingV of an edge.

Figure 3 is an enlarged detail view of a at, knurled and folded edge as seen in cross section.

t Figure 4v is a View showing schematically and in pfer-v The Width of the flat edge 2 determines the number 'of corrugations 3 toV which it can adhere, and thus the greater or less strength of the joint. Y

Moreover, extremity 4 of the edge 1 is gummed to side 5 of ,the first .existingy corrugation ofthe part of the flat edge 2, and thus, apart from increasing the strength of they joint, assures continuity of the pattern made by the corrugationsA and assists in giving a sightly lin-ish.

Another characteristic of the joint consists in the fact that the flat edge 2 is also knurled (Fig. 2) to compen- ,sate for the tendency of the cardboard or paper forming theA corrugatedjrnaterial a to lengthen in width under the liattening.- action and to counteract the tendency of the two lsheets of paper of which the corrugated material is `usually made to separate due to the loss of the corrugated form on the flattened part.

vTo avoid separation of the two sheets composing' the corrugated material the extreme edge of the at section 2 .'(Fig. 3) can beV bent over itself before theknurling action to form a fold 6 holding the two sheets together.

In the 4process, for forming tubes of corrugated material, joined according `tothis invention, the rectangle VofcorrugatedrnaterialtFig. 2) is first subjected tiranv operation, generally carried out by the machine which allows good adhesion without appreciably increasing the thickness of the joint.

Later the extreme surface of the edge 2, generally the portion corresponding to the last corrugation 3, is bent over itself, forming the fold 6 (Fig. 3). This operation avoids separation of the two sheets making up the corrugated material when the material used is of this type.

Immediately after this latter operation the flattened edge 2 is knurled with any suitable knurling pattern 7. The knurling pattern must be designed to keep the edge 2 fiat and of negligible thickness. The knurling pattern 7 `further functions to keep the two sheets of paper forming the corrugated material together, and to maintain correct length of the paper which would votherwise tend to lengthen to some length greater than that of the original sheet of corrugated material a.

In a later operation, the flattened and knurled edge V"2. and the external edge t of the opposite edge 1 are covered with' 4an adhesive coating.'

During the next step of folding round the rectangle of corrugated material a, the edge 1 is brought over `the iattened and knurled edge 2 (Fig. 1). As evident from Fig. 1 of the drawing edge 4 of the material is yformed along one of the ridges of the corrugated material. This edge is obtained by bisecting a ridge so as to form a plane surface which is later placed, as shown in Fig. l, along the side 5 of the first ridge of 'the corrugations on the flattened edge 2 side of the material.

' With the help of suitable heating above and below the joint region a rapid adhesion is effected of the corrugations 3 on the attened and knurled edge 2 and of the edge 4 on the side 5 of the corrugation 3.

This results in a tube having a joint which is very resistant to tensional forces to which it could be subjected during its use, for example, when the object to be protected (such as bottles, fluorescent tubes etc.) is

forced into it. At the same time the tube formed by the practice of this invention is aesthetically satisfactory due to the uniformity of spaced ridges and furrows of the corrugated material at the joint region.

The apparatus for producing tubes with edges joined as described hereinabove and as illustrated in Fig. 4 comprises upper and lower flattening plates 8 and 9, respectively, with the lower plate lowered with respect to its normal position to show the conformation of the flattening plate. A pair of knurling rollers 10 and 11 follow in the path of operation where the flattened edge is knurled prior to entering the forming tube 12 which cooperates with inner supporting tube 13. The side of the knurled edge 3 which is glued to the edge 1 of the corrugated material o r the edge 1 is provided with adhesive material in any convenient manner.

While only one embodiment ofthe invention has been described, it will be obvious to those skilled in the v`art that many variations and modifications can be made without departing from the scope of the invention.

I claim:

1. The method of joining edges of pliable and expansible corrugated material having ridges and furrows on both sides which comprises fiattening a plurality of ridges extending substantially parallel with and adjacentl to a first edge of said material, applying an adhesive coating to one. side of said first edge of said materal, overlapping asecond edge of said material having a corrugated border over said adhesive coated side of said first edge of said material, and disposing said *second edge of said ma- .terial adjacent a plane surface of the first row of ridges on said first edge of said material to form a corrugated surface of equally spaced ridges and furrows.

2. The method of joining the edges of a piece of pliable 'and expansible corrugated materialhavingplane side surfaced ridges and furrows on both sides extending 'longitudinally of said material which comprises Hattening a plurality of ridges extending substantially parallel rwith and adjacent to a first edge of said material, applying an adhesive coating to one side of said first edge of said material, forming a second edge of said material having a corrugated border along a plane surface of one side of a ridge of said material, applying an adhesive coating to the inside plane surface of said ridge, overlapping said second edge of said material over said adhesive coated side of said first edge of said material, and disposingsaid plane surface of said ridge of said second edge of said material adjacent the plane surface of the first row of ridges on said first edge of said material to formacorrugated surface of equally spaced ridges and furrows.

3. The method of joining first and second longitudinal edges of atube formed from a piece of pliable and expansible corrugated material having plane side surfaced ridges and furrowsr on both sides extending substantially parallelV with said longitudinal edges of said material and wherein said second longitudinal edge is formed along ajcorner of a bisected ridge of said material which comprises flattening a plurality of ridges formed adjacent said first longitudinal edge of said material, applying an adhesive coating to one side of the flattened surface of said first edge of said material and to the inside plane surface of the bisected ridge of said second edge of said material, overlapping said second edge of said material over said adhesive coated side of said first edge of said material,V disposing said plane surface of said bisected ridge of said second edge of said material 4adjacent the plane side surface of said iirst row of ridges on said first edge ofv said material to form an outer tubular corrugated surface of equally spaced ridges and furrows, and applying heat and pressure to said first and second edges of said material to dry the adhesive and secure said longitudinal edges of said tube together to form a pliable and expansible tube.

4. A joint for sealing the longitudinal edges of a tube formed from pliable and expansible corrugated material having plane side surfaced ridges and furrows on both sides extending longitudinally of said tube comprising a first longitudinal edge of said material forming a plane surface, a second longitudinal edge of said material overlapping said first edge of said material, said second edge of said material being disposed adjacent the first row of ridges on said first edge of said material to form a corrugated surface of equally spaced ridges and furrows, and

adhesive means provided on said plane surface of said first edge of saidmaterial to secure said longitudinal `edges of said tube together to lconstitute a pliable and expansible tube. p

5. A .joint'for sealing the longitudinal edges of a tube formed from pliable and expansible corrugated material having plane side surfaced ridges and'furrows on both sides extending longitudinally of said tube comprising a first longitudinal edge of said material forming a plane surface, a second longitudinal edge of said material formed along a plane surface of one side of a bisected ridge of said materialsaid second edge of said material arranged to overlap said first edge of said material with the plane surface of said bisected ridge o f said material being `disposed adjacent the plane surface of the first row of ridges on said first edge of said material to form a corrugated surface of equally spaced ridges and furrows, and adhesive means provided on said flattened surface ofrsaid first edge of said material and on the inside surface of said bisected ridge ofsaid second edge of said'material to secure said longitudinal edges,` of said tubetogether to constitute ka pliable and expansible tube. 6..A'joint for `sealing the longitudinal edges of a "tube'formed from pliable and expansible corrugated material having plane side surfaced ridges and furrows on .both sides exteudingvlongitudinally of said tube comprising a rst longitudinal edge of said .material forming a plane surface, the extremity of said firsty edge Vof said material being turned on itself, a second longitudinal4 .edge of said material formed along a planesurface of spaced ridges and furrows, and adhesive means provided on said attened surfaceof said rst edge oflsaid material and on the inside surface of said bisected ridge of said second edge of said material to secure said longitudinal edges of said tube together to constitute a pliable and expansible tube.

References cited in the me of this patent UNITED STATES PATENTS 154,498 Long Aug. 25, 1874 663.385 HobbsV Dec. 4, 1900 6 WhiteV Mar. l5, 1904 Bolger Mar. 17, 1914 Hawkins et al. June 30, 1914 Hawkins et al. June 30, 1914 Flipse Oct. 19, 1915 Swift Nov. 2, 1915 Quarnstrorn Ian. 24, 1933 Trageser et al. Mar. 27, 1934 Waters l Oct. 13, 1942 Platt Jan. 31, i950 Ryan Nov. 15, 1955 Magill July 16, 1957 FOREIGN PATENTS Australia Oct. 14, 1941 France Sept. 23, 1915 Denmark Feb.V 11, 1957 

3. THE METHOD OF JOINING FIRST AND SECOND LONGITUDINAL EDGES OF A TUBE FORMED FROM A PIECE OF PLIABLE AND EXPANSIBLE CORRUGATED MATERIAL HAVING PLANE SIDE SURFACED RIDGES AND FURROWS ON BOTH SIDES EXTENDING SUBSTANTIALLY PARALLEL WITH SAID LONGITUDINAL EDGES OF SAID MATERIAL AND WHEREIN SAID SECOND LONGITUDINAL EDGES IS FORMED ALONG A CORNER OF A BISECTED RIDGE OF SAID MATERIAL WHICH COMPRISES FLATTENING A PLURALITY OF RIDGES FORMED ADJACENT SAID FIRST LONGITUDINAL EDGE OF SAID MATERIAL, APPLYING AN ADHESIVE COATING TO ONE SIDE OF THE FLATTENED SURFACE OF SAID FIRST EDGE OF SAID MATERIAL AND TO THE INSIDE PLANE SURFACE OF THE BISECTED RIDGE OF SAID SECOND EDGE OF SAID MATERIAL, OVERLAPPING SAID SECOND EDGE OF SAID MATERIAL OVER SAID ADHESIVE COATED SIDE OF SAID FIRST EDGE OF SAID MATERIAL, DISPOSING SAID PLANE SURFACE OF SAID BISECTED RIDGE OF SAID SECOND EDGE OF SAID MATERIAL ADJACENT THE PLANE SIDE SURFACE OF SAID FIRST ROW OF RIDGES ON SAID FIRST EDGE OF SAID MATERIAL TO FORM AN OUTER TUBULAR CORRUGATED SURFACE OF EQUALLY SPACED RIDGES AND FURROWS, AND APPLYING HEAT AND PRESSURE TO SAID FIRST AND SECOND EDGES OF SAID MATERIAL TO DRY THE ADHESIVE AND SECURE SAID LONGITUDINAL EDGES OF SAID TUBE TOGETHER TO FORM A PLIABLE AND EXPANSIBLE TUBE. 